TM-Free and TM-Catalyzed Mechanosynthesis of Functional Polymers

Abstract

Mechanochemically induced methods are commonly used for the depolymerization of polymers, including plastic and agricultural wastes. So far, these methods have rarely been used for polymer synthesis. Compared to conventional polymerization in solutions, mechanochemical polymerization offers numerous advantages such as less or no solvent consumption, the accessibility of novel structures, the inclusion of co-polymers and post-modified polymers, and, most importantly, the avoidance of problems posed by low monomer/oligomer solubility and fast precipitation during polymerization. Consequently, the development of new functional polymers and materials, including those based on mechanochemically synthesized polymers, has drawn much interest, particularly from the perspective of green chemistry. In this review, we tried to highlight the most representative examples of transition-metal (TM)-free and TM-catalyzed mechanosynthesis of some functional polymers, such as semiconductive polymers, porous polymeric materials, sensory materials, materials for photovoltaics, etc.

Mechanochemical Degradation of Biopolymers

“…Although, at least in theory, all mechanochemical methods are suitable for preparing polymers [71][72][73][74], from a practical point of view, some of them are more appropriate for their destruction than preparation [75][76][77], since others are better for mastering or improving the physicochemical properties of a polymer [36,[78][79][80][81][82]. In polymer processing, chemical reactions often go unnoticed or only impact the material's physical properties.…”

Depolymerization of Polymethacrylates with Ball-Mill Grinding

“…Ball-mill grinding (BMG) is a popular technique used for polymer synthesis, − polymer degradation, − and other mechanochemical transformations. − Early studies pertaining to the BMG of PMMA were interested in the macroradicals that were generated upon chain scission. − Chain scission necessitates a reduction in the molecular weight, which will continue to decrease until reaching a limiting value (often referred to as the limiting molecular weight, M lim ). The M lim for PMMA is dependent on the grinding conditions, but has been reported to be as low as 5 or 6 kDa. ,, Thus, ball-milling of PMMA typically yields moderate to low molecular weight PMMA without depolymerization (Figure B).…”

Mechanosynthesis of Polyureas and Studies of Their Responses to Anions

“…In recent decades, mechanosynthesis has become an attractive tool for organic synthesis as a sustainable/greener alternative to conventional solvent-based conditions for carrying out chemical reactions [1][2][3][4]. The most remarkable example of such reactions is solvent-less or solvent-free polymerization for the preparation of functional polymers [5,6], including processes for the construction of coordination polymers [7] or supramolecular polymers [8] under mechanochemical conditions, most commonly under ball-milling ones.…”